There are many forms of medical implant devices, deployed transvascularly by means of a catheter, which are used where there is a requirement to occlude a vessel, fill a void or plug a defect in the treatment of medical conditions, whether they be acute or chronic situations or cosmetic situations.
These medical implant devices are delivered either transarterially or transvenously. The medical implant device is loaded in a folded or collapsed position within a tip of a catheter. The tip of the catheter is directed to the defect which is to be repaired and then the medical implant device is delivered from the catheter. Once out of the catheter the medical implant device is expanded to its full size to occlude the defect. Many of the known medical implant devices used are unsuitable for some applications because of their size and rigidity and we have proposed in certain co-pending patent applications the provision of a replacement technology for conventionally used coils, wire frame occlusion devices and the like. These improved implant devices have included the provision of highly compressible implant devices such as those having a compressible porous polymeric structure. One of the problems, however, with compressible devices and indeed many other devices is that they often do not react favourably to the conventional way of loading them in the catheter, which comprises pushing or pulling the implant into an end of the catheter. Very often by their very nature which allows them expand and assume the correct shape within the void this is the very construction that makes them difficult to push and manipulate. This also applies to other types of devices as well as implants having a compressible porous polymeric structure. Indeed what is required with most of these implants which can be loosely described as being expandable is that they be correctly compressed within the catheter. It is also desirable that if the implant device is initially deployed incorrectly or in the wrong location that the implant device can be easily loaded again in a collapsed position within the catheter for redeployment.
U.S. Pat. No. 5,683,451 discloses apparatus and a method for endoluminal placement of intraluminal tubular prostheses such as grafts and stents. The devices are collapsed within a distal end of a delivery catheter by a set of spaced-apart hard elongate runners mounted at a distal end of an inner catheter slidable within the delivery catheter.
WO 98/14224 discloses apparatus and a method for retrieving partially deployed balloon expandable stents from within a vein or artery. The apparatus has a grasping device comprising either an expandable tube or a plurality of spaced-apart nitinol fingers with elastomeric web stretched therebetween. The tube or fingers can be manipulated to open to grasp a stent and then closed to grip the stent for withdrawal into a catheter.
U.S. Pat. No. 5,026,377 discloses a device for the deployment or retraction of a self-expanding stent in a body canal. The device has a tubular outer sleeve and an inner core slidable within the sleeve, the stent being collapsed against the core and being held in the collapsed state between the core and the outer sleeve for deployment.
It is an object of the present invention to provide a catheter that has the ability to deliver devices that don't have axial stiffness.